Classic Apps had screen styles that could be List Only. What this means is that you could have a list on the screen but no other components. Because of that, it did make more sense to have an Add button at the top right of the screen because that Add button could only pertain to the single list. With the new Apps, there is no such thing as a List Only screen. All screens are detail screens, so you could have multiple lists mixed with multiple other components.
As for the Edit button, that pertains to the current detail screen, so you can edit only the row you are viewing.
I would argue that the new way is a lot more flexible in many ways, but that is my own personal opinion. Within each individual collection on the screen, you can enable an Add button, or you can enable edit buttons directly on each item.

If you are viewing the details for an item, you have some options including using an Action Row component to display an Edit button, or adding actions to various components.
Itās not exactly in the corner, but you also have to consider how it will look on a larger screen as well.
You just need to be willing to think outside the box a little bit and play with your options. You may not get exactly what you want, but I think you can usually get something that works just as well and in some cases might be better in the long run.
You will always have to design Add screens, Edit Screens, and Forms independently. They will not automatically follow your design of a Detail screen.
This is coming. Itās on Glideās immediate roadmap.
The Glide Docs team is working hard. It takes time to reshoot and edit new videos on a platform that is ever changing. There is a lot of material for them to relearn as well. Yes, I understand itās confusing, but itās a transition process. Itās only been a week since they officially locked down Classic Apps and officially changed the names of the products. Before that, itās been a few months of transition and I foresee it continuing into next year before everything is 100% Apps.
Confusing time to be a new user Iām sure.